JP5636290B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure-sensitive conductive rubber member used in a pressure-sensitive sensor that detects a change in load by a change in electric resistance value, and also relates to a pressure-sensitive sensor using the pressure-sensitive conductive rubber member.

  Conventionally, a method using piezoelectric ceramics such as lead zirconate titanate or a method using a strain gauge has been used as means for measuring the magnitude and distribution of pressure acting on a member. However, since the method using piezoelectric ceramics generally uses a material with high rigidity, the degree of freedom of the shape of the pressure sensor is limited, and the method using a strain gauge is also similar to the shape of the pressure sensor. There is a problem that the degree of freedom of design is low.

  With respect to these problems, a polymer material such as rubber, elastomer, resin material, etc. is used as a base material, and a pressure-sensitive member in which conductive particles are dispersed in this base material is used. It is known that a pressure sensor can be obtained.

  For example, a pressure-sensitive conductive elastomer is reported in which hollow elastic microspheres having a particle size of 10 to 150 μm are dispersed together with fine spherical carbon particles having a particle size of 1 to 20 μm in a non-conductive elastomer. (Patent Document 1). Since this pressure-sensitive conductive elastomer uses hollow elastic microspheres, it is possible to obtain a pressure-sensitive conductive elastomer with excellent durability and shock absorption and improved hysteresis of pressure-resistance change. It becomes.

  A film-like pressure sensitive resistor having an average surface roughness of 0.1 μm or more and 3 μm or less, a peak of the surface irregularity period of 10 μm or more and 1,000 μm or less, and an elastic modulus of 800 MPa or more and 8,000 MPa or less. It has been reported (Patent Document 2). This film-like pressure-sensitive resistor has a sufficient average surface roughness, peak surface irregularity period, and elastic modulus, so that the contact area gradually changes even when the load changes in the low load region at the initial stage of contact. It is.

Japanese Patent Laid-Open No. 4-71108 JP 2002-158103 A

However, the pressure-sensitive conductive elastomer of Patent Document 1 has the following problems.
(1) Even if hollow elastic microspheres rich in elasticity are used, a strong hysteresis loss may occur in the detection resistance value due to the adhesiveness of the pressure-sensitive conductive elastomer, and the reliability of the pressure-sensitive characteristics Lack.
(2) Since the elastic modulus of the pressure-sensitive conductive elastomer is low, the amount of deformation of the elastomer gradually increases when a constant force is applied to the sensor, and the output (electric resistance value) changes significantly with time.

The film-shaped pressure sensitive resistor disclosed in Patent Document 2 has the following problems.
(1) Even if the film-like pressure sensitive resistor has a sufficient average surface roughness, a peak of the surface irregularity period and an elastic modulus, if the substrate is not an elastic body, the contact state between the film-like pressure sensitive resistor and the electrode The uniformity of the pressure is poor, the reproducibility may be inferior when the load-unloading test is repeated, and the pressure-sensitive characteristics are not reliable.
(2) Since the elastic modulus of the film-like pressure sensitive resistor is high, the contact state between the film-like pressure sensitive resistor and the electrode is messy, and the output is constant when a constant force is applied to the sensor. It may not be kept.

  Therefore, the problems of the present invention are that the hysteresis loss is small, the amount of change in output when a constant force is applied to the sensor is very small (= good drift), and the change in electrical resistance value due to deformation is excellent. It is to provide a pressure-sensitive conductive rubber member having high reproducibility and high reliability, and to provide a pressure-sensitive sensor using the pressure-sensitive conductive rubber member.

The present invention, by detecting a change in the conduction resistance of the pressure sensitive conductive rubber member and the electrode in response to changes in load, Oite pressure-sensitive sensor that senses a load, sensitive pressure sensors, flat has between Ru formed of at least two layers sensitive conductive rubber member and a resin coating containing a rubber substrate and a conductive agent, an electrode facing contact with the resin coated surface of the photosensitive-pressure conductive rubber member, Of the elastic modulus measured with a dynamic ultra-micro hardness meter, when the elastic modulus of the rubber base material is E1, and the elastic modulus of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed is E2, E1 is 0.5 MPa or more and 30 MPa or less , E2 is 10 MPa or more and 700 MPa or less, and the ratio of elastic modulus E1 and elastic modulus E2 is 1 <E2 / E1 <1,000. It is a pressure sensitive sensor .

Moreover, this invention is the said pressure sensor, Comprising: The said electrode is a flexible printed circuit board, It is a pressure sensor characterized by the above-mentioned.

  According to the present invention, hysteresis loss is small, the amount of output change with time when a constant force is applied to the sensor is extremely small (= good drift), and the electrical resistance value change due to deformation is excellent reproduction There is provided a pressure-sensitive conductive rubber member for a pressure-sensitive sensor having high reliability and high detectability. Further, by using this pressure-sensitive conductive rubber member, a pressure-sensitive sensor having excellent reproducibility and highly reliable detection of changes in electrical resistance value due to deformation is provided.

It is sectional drawing of the pressure-sensitive conductive rubber member which concerns on this invention. FIG. 1 (a) is a two-layer structure, FIG. 1 (b) is a form in which a three-layer resin coating is coated, and FIG. 1 (c) is a resin film coating around the substrate. It is a form. It is a top view of the flexible printed circuit board electrode used for the pressure sensor which concerns on this invention. 2A shows a comb-type electrode, and FIG. 2B shows a square plate-type electrode. It is sectional drawing of the pressure-sensitive sensor which concerns on this invention. FIG. 3A shows the case where the pressure-sensitive conductive rubber member 1a and the comb-shaped electrode 2a are used, and FIG. 3B shows the case where the pressure-sensitive conductive rubber member 1b and the square plate-type electrode 2b are used. It is a schematic diagram which shows the measuring method of the pressure and electrical resistance value in a load-unloading test. It is a figure which shows the relationship between the pressure of the load-unloading test in Example 1, and electrical resistance value LogR.

The pressure-sensitive conductive rubber member in the present invention is a pressure-sensitive conductive rubber used in a pressure-sensitive sensor that senses a load by detecting a change in conduction resistance value between the pressure-sensitive conductive rubber member and the electrode in accordance with a change in load. It is a member. This pressure-sensitive conductive rubber member is formed of at least two layers including a rubber base material and a resin coating film containing a conductive agent. Of the elastic modulus measured by a dynamic ultra-micro hardness meter , the rubber when the elastic modulus of the base material E1, the elastic modulus of the pressure-sensitive conductive rubber member of the resin coating film is formed faces the E2, elastic modulus E1 is, 0.5 MPa or more, 30 MPa or less, the elastic modulus E2 Is 10 MPa or more and 700 MPa or less, and the ratio between the elastic modulus E1 and the elastic modulus E2 is 1 <E2 / E1 <1,000.

The pressure-sensitive conductive rubber member in the present invention has at least a two-layer structure in which a resin coating film containing a conductive agent is formed on the surface of a rubber base material. Fig.1 (a)-FIG.1 (c) have shown sectional drawing of the pressure-sensitive conductive rubber member of this invention. FIG. 1A shows a pressure-sensitive conductive rubber member 1a having a two-layer structure in which a resin coating film 1a-2 is formed on one surface of a rubber substrate 1a-1. FIG. 1B shows a pressure-sensitive conductive rubber member 1b having a three-layer structure in which a resin coating film 2b-1 is formed on both surfaces of a rubber substrate 1b-1. As shown in FIG. 1C, the pressure-sensitive conductive rubber member 1c may be formed in a form in which a resin coating film 1c-2 is formed around the rubber base material 1c-1.

[Rubber substrate]
The rubber base material is an elastic body that has an action of elastically deforming with compression and smoothly changing a conduction resistance change with an electrode disposed opposite to the pressure-sensitive conductive rubber member.

  Specific examples of the rubber component of the unvulcanized rubber composition used as a raw material for the rubber base material include the following. Natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), ethylene propylene rubber (EPM, EPDM), chloroprene rubber (CR), isoprene rubber (IR), epichlorohydrin rubber ( CO, ECO), silicone rubber, urethane rubber (U) and the like. These rubber components can be used alone or in admixture of two or more. The rubber composition usually contains various compounding agents in addition to the rubber component. For example, those conventionally used as rubber compounding agents such as conductivity imparting agents, vulcanizing agents, vulcanization accelerators, fillers, anti-aging agents, anti-scorching agents, softeners, plasticizers, dispersants, etc. Mix appropriately. The unvulcanized rubber composition can be mixed using, for example, a kneader such as a pressure kneader or an open roll.

  The method for molding and crosslinking the unvulcanized rubber composition is not particularly limited, and examples of the molding method include extrusion molding and press molding. Extrusion molding is a method in which the unvulcanized product is kneaded with a screw and passed continuously through an extrusion die (die) at the tip. Press molding is a method in which a mold is filled with the above unvulcanized product and pressure molded. The vulcanization method for the unvulcanized rubber mixture after molding is not particularly limited as long as the vulcanization is performed by temperature control such as heating and cooling.

  The elastic modulus of the rubber base material is 0.5 MPa or more and 30 MPa or less, and more preferably 1.0 MPa or more and 20 MPa or less. If it is in the said range, the elastic rubber base material which has an effect | action which elastically deforms with compression and the conduction resistance change with the electrode arrange | positioned facing a pressure-sensitive conductive rubber member will change smoothly will be obtained. If the elastic modulus is less than 0.5 MPa, the rubber base material is immediately deformed with compression, and the pressure sensor functions as an on-off switch. If the elastic modulus is larger than 30 MPa, the rubber base material cannot be elastically deformed following the increase and decrease of the load, and the detection resistance value does not become a smooth curve.

  The thickness d1 of the rubber base material is not particularly limited, but is preferably 0.1 mm ≦ d1 ≦ 10 mm. If the thickness of the rubber base material is 0.1 mm or more, the rubber base material is elastically deformed with compression, and the conduction resistance between the pressure-sensitive conductive rubber member and the electrode is appropriately changed. If the thickness of the rubber substrate is 10 mm or less, the size of the pressure-sensitive conductive rubber member can be reduced, and the degree of freedom of the shape of the pressure-sensitive sensor can be increased.

Further, the electrical resistance value of the rubber base material is appropriately adjusted depending on the configuration of the electrode when used as a pressure-sensitive conductive rubber member and as a pressure-sensitive sensor. When electrodes are arranged on one side as shown in FIG. 3 (a), electricity is conducted through the resin coating film, so that the electric resistance value of the rubber base material is not particularly limited. When electrodes are arranged on both sides as shown in FIG. 3 (b), electricity is conducted through the rubber base material. Therefore, the electrical resistance value of the rubber base material is preferably 10 ³ Ω · cm or less. If it is 10 ³ Ω · cm or less, an electrical conduction change corresponding to the load can be obtained through the pressure-sensitive conductive rubber member.

[Resin coating film]
The pressure-sensitive conductive rubber member is formed of a resin coating containing a conductive agent on the surface of the rubber base material to form two or more layers. Functions as a detecting element. Hereinafter, a resin coating film containing a conductive agent is simply expressed as “resin coating film”.

  Specifically, the following are mentioned as a resin component which comprises a resin coating film. Fluorine resin, polyamide resin, acrylic resin, polyurethane resin, polyester resin, epoxy resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC) and olefin-ethylene-butylene-olefin copolymer (CEBC) )etc. These resins may be used alone or in combination of two or more. In addition, the resin may be a cross-linked resin, and for example, an isocyanate compound and an amine compound can be appropriately blended as a curing agent in the coating composition as a raw material for the resin coating film.

Moreover, in order to obtain a desired electrical resistance value, the resin coating film is made of conductive carbon, graphite, copper, aluminum, nickel, iron powder and conductive oxides such as conductive tin oxide and conductive titanium oxide which are metal oxides. Containing. These may be used alone or in combination of two or more. The electric resistance value of the resin coating film is not particularly limited, but is preferably 10 ^-1 Ω · cm or more and 10 ³ Ω · cm or less under a pressure of 500 kPa or more. If it is 10 ⁻¹ Ω · cm or more, the insulation is maintained when no pressure is applied, and a change in conduction according to the load is obtained when pressure is applied. If it is 10 ³ Ω · cm or less, no output is obtained even when a load is applied, and an output corresponding to the load is obtained.

  In addition to the resin and conductive particles, other components can be blended, and examples thereof include organic elastic fillers, inorganic oxide fillers, and dispersants.

  Regarding the method of forming the resin coating film, first, the material constituting the resin coating film, and the coating composition composed of an organic solvent, etc., using a dispersing device using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill. Prepare. The obtained coating composition is applied to the surface of the rubber substrate by dipping or spray coating. In consideration of the utilization efficiency of the coating composition, the dipping method is preferable. Further, the solvent is removed using a hot air circulating dryer or an infrared drying furnace to form a resin coating on the surface of the rubber substrate.

  If the wettability between the rubber base material and the coating composition is not good, the surface free energy is increased by irradiating the rubber base material with ultraviolet rays or a primer is applied to the rubber base material before coating. Thus, it is possible to form a uniform coating film by improving the wettability.

  The resin coating may be formed on at least one surface of the elastic rubber substrate. When the pressure-sensitive conductive rubber member of the present invention is used as a pressure-sensitive sensor, the resin coating is applied to the electrodes on a substrate on which at least a pair of electrodes are formed. What is necessary is just to arrange | position a pressure-sensitive conductive rubber member so that a film | membrane opposes.

  The elastic modulus of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed is 10 MPa or more and 700 MPa or less, and more preferably 50 MPa or more and 600 MPa or less. If the elastic modulus is 10 MPa or more, the amount of deformation does not increase with time when a constant force is applied to the sensor, and the electrical resistance value does not increase with time. If the elastic modulus is 700 MPa or less, the flexibility as a member is good, the uniformity of the contact state with the electrode is maintained, and the reproducibility when the load-unloading test is repeated is good. Further, the contact state is kept uniform when a certain force is applied to the sensor, and there is no possibility that the output changes with time.

  The film thickness d2 of the resin coating film is not particularly limited, but 5 μm ≦ d2 ≦ 100 μm is preferable. When the film thickness of the resin coating film is 100 μm or less, the flexibility as the pressure-sensitive conductive rubber member is maintained, and the contact area changes according to the change in load. Moreover, if the film thickness of the resin coating film is 5 μm or more, a desired elastic modulus is obtained as a pressure-sensitive conductive rubber member, and the amount of deformation does not gradually increase when a certain force is applied to the sensor, There is also no risk of the output changing over time.

The ratio of the elastic modulus E1 of the rubber substrate and the elastic modulus E2 of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed is 1 <E2 / E1 <1,000. When E2 / E1 is 1 or less, the elastic modulus E2 of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed is not larger than the elastic modulus E1 of the rubber substrate, and the resin coating film is formed. Due to the low elastic modulus of the pressure-sensitive conductive rubber member on the other surface, there is a problem that the amount of deformation gradually increases when a constant force is applied to the sensor, and the output changes greatly with time. In addition, there is a problem that a strong hysteresis loss occurs in the detection resistance value due to the adhesiveness of the pressure-sensitive conductive rubber member.

When E2 / E1 is 1,000 or more, it is derived from the high elastic modulus of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed , and is inferior in the uniformity of the contact state with the electrode. There is a problem that the reproducibility is poor when the load test is repeated. Further, when a constant force is applied to the sensor, it is difficult to maintain a uniform contact state, and there is a problem that the output changes with time.

〔electrode〕
Pressure-sensitive sensor according to the present invention, there is provided a pressure sensor comprising an electrode facing contact with the resin coated surface of at least the pressure-sensitive conductive rubber member and the photosensitive-pressure conductive rubber member, the flexible printed circuit board as the electrode Can be arranged.

  A flexible printed circuit board electrode as shown in FIG. 2 is used as the electrode of the pressure sensitive sensor. FIG. 2A is a plan view of the comb-shaped electrode 2a, which includes a wiring 2a-1 made of a conductive metal such as copper or silver paste and a substrate 2a-2 made of an insulating resin such as polyimide or polyester film. Is formed. FIG. 2B is a plan view of the square plate-type electrode 2b. The wiring 2b-1 is made of a conductive metal such as copper or silver paste, and the substrate 2b-2 is made of an insulating resin such as polyimide or polyester film. It is formed with.

  FIG. 3 shows a cross-sectional view of a pressure-sensitive sensor using the pressure-sensitive conductive rubber member of the present invention. FIG. 3A shows a pressure-sensitive sensor 3a disposed so that the resin coating surface 1a-1 of the pressure-sensitive conductive rubber member 1a is opposed to the wiring 2b-1 side of the comb-shaped electrode 2a. The pressure-sensitive conductive rubber member 1a is elastically deformed according to the load-unloading of the load P with respect to the pressure-sensitive sensor 3a, and the conduction resistance changes. FIG. 3B shows a pressure-sensitive sensor 3b that is disposed with a pressure-sensitive conductive rubber member 1b sandwiched so that the wiring 2b-1 side of the square plate-type electrode 2b faces each other. The pressure-sensitive conductive rubber member 1b is elastically deformed and the conduction resistance is changed according to the load-unloading of the load P with respect to the pressure-sensitive sensor 3b.

Hereinafter, the pressure-sensitive sensor of the present invention will be specifically described with reference to examples and comparative examples.

Example 1
<1. Fabrication of substrate>
The following materials were mixed with two rolls for 20 minutes to produce an unvulcanized rubber compound.
・ 70 parts by mass of butadiene rubber (trade name “BR150” manufactured by Ube Industries, Ltd.)
-30 parts by mass of isoprene rubber (manufactured by Nippon Zeon Co., Ltd., trade name “IR2200”),
-5 parts by mass of zinc oxide (manufactured by Hakusui Tech Co., Ltd., trade name “Zinc Hana 2”),
-1 part by weight of zinc stearate (Nippon Yushi Co., Ltd., trade name “zinc stearate”),
・ 10 parts by mass of carbon black (product name “SEAST TA” manufactured by Tokai Carbon Co., Ltd.)
・ 2 parts by mass of sulfur (trade name “Sulfax PMC”, manufactured by Tsurumi Chemical Co., Ltd.)
-1 part by mass of TETD (tetraethyl thiuram disulfide) (Ouchi Shinsei Chemical Co., Ltd., trade name "Noxeller TET"),
MBTS (dibenzothiazyl disulfide) (manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller DM”) 1 part by mass.

  Next, the unvulcanized product is filled in a mold having a length of 150 mm, a width of 150 mm, and a depth of 2.0 mm preheated to 170 ° C., and press vulcanized at 170 ° C. and 100 kgf for 15 minutes to form a flat plate shape. A rubber substrate was obtained.

<2. Preparation of coating composition>
Subsequently, the following materials were blended to prepare a resin solution having a solid content of 30% by mass.
-100 parts by weight of polyol (manufactured by Daicel Chemical Industries, Ltd., trade name "Placcel DC2016 (solid content 70%, hydroxyl value 80 mgKOH / g)")
-25 parts by mass of isophorone diisocyanate curing agent (manufactured by Degussa Huls, trade name "Vestanat B1370 (solid content 60%, NCO 8.0%)")
-Hexamethylene diisocyanate curing agent (Asahi Kasei Kogyo Co., Ltd., trade name "Duranate TPA-B80E (solid content 80%, NCO 12.5%)") 32 parts by mass (NCO / OH ratio = 1.0),
・ 55 parts by mass of carbon black (trade name “# 3230” manufactured by Mitsubishi Chemical Corporation),
-Modified dimethyl silicone oil (Toray Dow Corning Silicone Co., Ltd., trade name "SH-28PA") 0.05 parts by mass,
-340 mass parts of MIBK (methyl isobutyl ketone).

  To 200 parts by mass of this resin solution, 200 parts by mass of glass beads having a diameter of 0.8 mm were added, placed in a 450 ml mayonnaise bottle, and dispersed for 6 hours using a paint shaker. Finally, the solution was filtered through a 200 mesh screen to prepare a coating composition.

<3. Production of pressure-sensitive conductive rubber member>
The flat rubber substrate is vertically immersed in the coating composition at a pulling rate of 200 mm / sec, held for 10 seconds, and then pulled up at a pulling rate of 10 mm / sec to apply the coating composition on the surface of the rubber substrate. Worked. In addition, the said coating was performed at room temperature. Next, after air-drying at room temperature for 30 minutes, an oven is used to cure by heating at 160 ° C. for 1 hour to obtain a pressure-sensitive conductive rubber member having a 13 μm-thick resin coating formed on the surface of the rubber substrate. It was.

<4. Measurement of elastic modulus>
For the measurement of the elastic modulus, “Shimadzu Dynamic Ultra Hardness Tester” DUH-W201S manufactured by Shimadzu Corporation was used. The measurement conditions are: test mode: load-unload test, load speed: 0.28 mN / sec, holding time: 5 sec, indenter type: triangular pan indenter 115. The test force was adjusted so that the indentation depth of the indenter was 1/10 or less of the thickness of the measurement object. That is, when the thickness of the rubber base material was 2.0 mm, the test force was adjusted so that the indentation depth was 0.2 mm or less. When the thickness of the resin coating film was 13 μm, the test force was adjusted so that the indentation depth was 1.3 μm or less. The elastic modulus of the rubber base material was obtained by pressing a triangular pan indenter into the surface of the flat rubber base material. The elastic modulus of the pressure-sensitive conductive rubber member on the surface on which the resin coating film was formed was determined by pressing a triangular pan indenter into the surface of the resin coating film of the pressure-sensitive conductive rubber member. The results are shown in Table 1.

<5. Load detection performance as a pressure sensor>
The obtained pressure-sensitive conductive rubber member was cut into 10 mm length and 10 mm width, and the square sheet was left in a 23 ° C., 60% RH (N / N) environment for 24 hours or more, and as shown in FIG. The pressure-sensitive rubber member resin coating was placed so as to face the flexible printed circuit board comb electrode (electrode width: 1 mm, electrode spacing: 0.5 mm) to form a pressure-sensitive sensor so that a load was applied to the entire top surface of the square sheet. .

  In this state, a DC voltage of 5 V is applied to the comb-shaped electrode, and a load measuring device is loaded and unloaded at a speed of 5 mm / min in the thickness direction of the pressure-sensitive sensor within a range of 0 to 50 kPa. The voltage applied to a 1 kΩ resistor connected in series to the was detected and measured. The electrical resistance value was calculated from the voltage value at each load. The results are shown in FIG.

1) Hysteresis loss For each load, obtain the absolute value of the difference between the electrical resistance value at the time of loading (LogR _load ) and the electrical resistance value at the time of unloading (LogR _unloading ), and use this maximum value as an index of hysteresis loss. Displayed according to the following criteria. The results are shown in Table 1.
A: | Maximum value Δ (LogR _load− LogR _unloading ) | ≦ 0.1
○: 0.1 <| maximum value Δ (LogR _load− LogR _unloading ) | ≦ 0.3
Δ: 0.3 <| maximum value Δ (LogR _load− LogR _unloading ) | ≦ 0.5
×: 0.5 <| maximum value Δ (LogR _load− LogR _unloading ) |

2) Reproducibility The load-unloading test was repeated 100 times, and the reproducibility of the detected resistance value in repeated load-unloading was evaluated. The standard deviation (3σ) of the value measured 100 times at each load of the electrical resistance value at the time of loading (LogR _load ) and the value measured 100 times at each load of the electrical resistance value at the time of unloading (LogR _unloading ) A standard deviation (3σ) was determined, and the maximum value (3σ _max ) was used as an index of reproducibility. The results are shown in Table 1.
A: 3σ _max ≦ 0.3
○: 0.3 <3σ _max ≦ 0.4
Δ: 0.4 <3σ _max ≦ 0.5
X: 0.5 <3σ _max .

3) Drift Load is applied to the pressure sensor in the thickness direction of the pressure sensor at a speed of 5 mm / min up to 15 kPa, and is applied to a 1 kΩ resistor connected in series to the comb electrode while maintaining this constant load of 15 kPa. The voltage was detected and measured for 10 hours. The electric resistance value was calculated from the voltage value at each time. The absolute value of the difference between the initial electrical resistance value (the _initial LogR _drift ) and the electrical resistance value after 10 hours ( _{after 10 hours of} LogR _drift ) was obtained and displayed as an index of output fluctuation at constant load according to the following criteria. The results are shown in Table 1.
｜: | Δ (LogR _{drift initial} stage—LogR _{drift 10 hours later} ) | ≦ 0.1
○: 0.1 <| Δ (LogR _{drift initial} stage—LogR _{drift 10 hours later} ) | ≦ 0.3
Δ: 0.3 <| Δ (LogR _{drift initial} stage−LogR _{drift 10 hours later} ) | ≦ 0.5
×: 0.5 <| Δ (LogR _{drift initial} stage−LogR _{drift 10 hours later} ) |

Moreover, the comprehensive judgment of the load detection performance as a pressure sensor was performed on the following reference | standard. The results are shown in Table 1.
Best: In each evaluation of hysteresis loss, reproducibility, and drift, only ◎.
Good: In each evaluation of hysteresis loss, reproducibility, and drift, ○ is included. (△ and below are not included.)
Yes: In each evaluation of hysteresis loss, reproducibility, and drift, Δ is included. (X and below are not included.)
Inappropriate: In each evaluation of hysteresis loss, reproducibility, and drift, x is included.

(Example 2)
A pressure-sensitive conductive rubber member was obtained in the same manner as in Example 1 except that an unvulcanized rubber compound was prepared with the following composition. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.
・ 200 parts by mass of ethylene propylene rubber (manufactured by Sumitomo Chemical Co., Ltd., trade name “Esprene 600F (oil expansion amount 100 phr)”),
・ 10 parts by mass of carbon black “Seast TA”
・ 8 parts by mass of dicumyl peroxide (Nippon Yushi Co., Ltd., trade name “Park Mill D-40MB”),
Trial isocyanurate (Nihon Kasei Co., Ltd., trade name “TAIC-WH60”) 3 parts by mass.

Example 3
The following materials were blended to prepare an unvulcanized rubber compound.
・ 70 parts by mass of butadiene rubber “BR150”,
-Isoprene rubber "IR2200" 30 parts by mass,
-5 parts by mass of zinc oxide "Zinc flower 2 types"
-50 parts by mass of carbon black (manufactured by Asahi Carbon Co., Ltd., trade name "Asahi F-200")
-3 parts by mass of dicumyl peroxide “Park Mill D-40MB”.

  In addition, a coating composition having a solid content of 37% by mass was prepared with the blending part of the solvent MIBK being 235 parts by mass. Otherwise, a pressure-sensitive conductive rubber member having a 38 μm-thick resin coating film was obtained in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
A pressure-sensitive conductive rubber member having a resin coating film with a film thickness of 63 μm formed in the same manner as in Example 1 except that a coating composition having a solid content of 43% by mass was prepared by setting the blending part of the solvent MIBK to 173 parts by mass. Obtained. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
The following materials were blended to prepare a coating composition having a solid content of 37% by mass.
-100 parts by weight of polyol "Placcel DC2016"
-45 parts by mass of isophorone diisocyanate curing agent "Vestanat B1370"
-29 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.2),
-MIBK244 mass part.
Otherwise, a pressure-sensitive conductive rubber member having a 38 μm-thick resin coating film was obtained in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
The following materials were blended to prepare an unvulcanized rubber compound.
-200 parts by mass of ethylene propylene rubber "Esprene 600F"
・ 5 parts by mass of carbon black “Seast TA”
-5 parts by mass of dicumyl peroxide "Park Mill D-40MB"
-2 parts by mass of triallyl isocyanurate “TAIC-WH60”.

Moreover, the following materials were mix | blended and the coating composition with a solid content of 20 mass% was produced.
-100 parts by weight of polyol "Placcel DC2016"
-48 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.0),
-MIBK612 mass part.
Other than that was carried out similarly to Example 1, and obtained the pressure-sensitive conductive rubber member in which the resin coating film with a film thickness of 3 micrometers was formed. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
The following materials were blended to prepare an unvulcanized rubber compound.
・ 80 parts by mass of butadiene rubber “BR150”,
・ 20 parts by mass of high styrene rubber (manufactured by JSR Corporation, trade name “JSR0061”),
-5 parts by mass of zinc oxide "Zinc flower 2 types"
・ 50 parts by mass of carbon black “Asahi F-200”,
-5 mass parts of dicumyl peroxide "Park mill D-40MB".

Further, the following materials were blended to prepare a coating composition having a solid content of 37% by mass.
-100 parts by weight of polyol "Placcel DC2016"
-45 parts by mass of isophorone diisocyanate curing agent "Vestanat B1370"
-29 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.2),
-MIBK244 mass part.
Otherwise, a pressure-sensitive conductive rubber member having a 38 μm-thick resin coating film was obtained in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
The following materials were blended to prepare an unvulcanized rubber compound.
・ 80 parts by mass of butadiene rubber “BR150”,
・ 20 parts by mass of high styrene rubber “JSR0061”
・ Zinc oxide "Zinc Hana 2 types" 5 parts,
・ 50 parts by mass of carbon black “Asahi F-200”,
-5 mass parts of dicumyl peroxide "Park mill D-40MB".

Moreover, the following materials were mix | blended and the coating composition with a solid content of 20 mass% was produced.
-100 parts by weight of polyol "Placcel DC2016"
-48 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.0),
-MIBK612 mass part.
Other than that was carried out similarly to Example 1, and obtained the pressure-sensitive conductive rubber member in which the resin coating film with a film thickness of 3 micrometers was formed. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 9
The following materials were blended to prepare an unvulcanized rubber compound.
-200 parts by mass of ethylene propylene rubber "Esprene 600F"
・ 5 parts by mass of carbon black “Seast TA”
-5 parts by mass of dicumyl peroxide "Park Mill D-40MB"
-2 parts by mass of triallyl isocyanurate “TAIC-WH60”.

Moreover, the following materials were mix | blended and the coating composition with a solid content of 34 mass% was produced.
-100 parts by weight of polyol "Placcel DC2016"
-45 parts by mass of isophorone diisocyanate curing agent "Vestanat B1370"
-29 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.2),
-MIBK286 mass part.
Otherwise, a pressure-sensitive conductive rubber member having a resin coating film having a thickness of 23 μm was obtained in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
The following materials were blended to prepare an unvulcanized rubber compound.
-200 parts by mass of ethylene propylene rubber "Esprene 600F"
・ 5 parts by mass of carbon black “Seast TA”
-5 parts by mass of dicumyl peroxide "Park Mill D-40MB"
-2 parts by mass of triallyl isocyanurate “TAIC-WH60”.

Further, the following materials were blended to prepare a coating composition having a solid content of 37% by mass.
-100 parts by weight of polyol "Placcel DC2016"
-45 parts by mass of isophorone diisocyanate curing agent "Vestanat B1370"
-29 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.2),
-MIBK244 mass part.
Otherwise, a pressure-sensitive conductive rubber member having a 38 μm-thick resin coating film was obtained in the same manner as in Example 1. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
A polyester film (trade name “Tough Top # 188 B2T0” manufactured by Toray Film Processing Co., Ltd.) was used as the substrate. Moreover, the following materials were mix | blended and the coating composition with a solid content of 20 mass% was produced.
-100 parts by weight of polyol "Placcel DC2016"
-48 parts by mass of hexamethylene diisocyanate curing agent “Duranate TPA-B80E” (NCO / OH ratio = 1.0),
-MIBK612 mass part.
Other than that was carried out similarly to Example 1, and obtained the pressure-sensitive conductive rubber member in which the resin coating film with a film thickness of 3 micrometers was formed. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
The following materials were mixed with two rolls for 20 minutes to produce an unvulcanized rubber compound.
・ 100 parts by mass of silicone rubber (manufactured by Shin-Etsu Silicone Co., Ltd., trade name “KE-650U”),
-50 parts by mass of hollow elastic microsphere (Matsumoto Yushi Seiyaku Co., Ltd., trade name "M600"),
-50 parts by mass of fine spherical carbon particles (manufactured by Nippon Carbon Co., Ltd., trade name “carbon microbead ICB0510”),
-2 parts by mass of dicumyl peroxide “Park Mill D-40MB”.

  Next, the unvulcanized product was filled in a 150 mm long, 150 mm wide, 2.0 mm deep mold preheated to 170 ° C., and press vulcanized at 170 ° C. and 100 kgf for 15 minutes to obtain pressure-sensitive pressure. A conductive rubber member was obtained. Various evaluations were performed in the same manner as in Example 1 using this pressure-sensitive conductive rubber member. The results are shown in Table 1.

  In Examples 1, 2, and 3, it can be seen that excellent pressure loss, reproducibility, and drift can be provided, and a suitable pressure-sensitive sensor can be provided by applying this pressure-sensitive conductive rubber member. In Examples 4 and 5, due to the high elastic modulus of the pressure-sensitive conductive rubber member, the uniformity of the contact state with the electrode is slightly inferior, and the reproducibility when the load-unloading test is repeated is inferior. Although there is a tendency, hysteresis loss and drift are excellent, and it can be seen that the pressure sensor is good.

  In Example 6, due to the low elastic modulus of the pressure-sensitive conductive rubber member, the pressure-sensitive conductive rubber member has adhesiveness, and the hysteresis loss tends to be inferior to the detection resistance value. Also, due to the low elastic modulus of the pressure-sensitive conductive rubber member, the amount of deformation gradually increases when a constant force is applied to the sensor, and the output tends to change over time. Since the rubber member has an appropriate flexibility, even when the load-unloading test is repeated, the output is excellent in output reproducibility and can be applied as a pressure-sensitive sensor.

  In Example 7, due to the high elastic modulus of the pressure-sensitive conductive rubber member, the uniformity of the contact state with the electrode is slightly inferior, and the reproducibility tends to be inferior when the load-unloading test is repeated. is there. Also, due to the high elastic modulus of the rubber base material and the high elastic modulus of the pressure-sensitive conductive rubber member, it is difficult to maintain a uniform contact state when a certain force is applied to the sensor, and the output However, since the pressure-sensitive conductive rubber member has an appropriate flexibility, the hysteresis loss is excellent and can be applied as a pressure-sensitive sensor.

  In Example 8, since the elastic modulus ratio E2 / E1 is small and the elastic modulus of the pressure-sensitive conductive rubber member is relatively low, it is gradually deformed when a certain force is applied to the sensor. The amount increases and the output tends to change over time. In addition, the hysteresis loss tends to be inferior in the detection resistance value due to the adhesiveness of the pressure-sensitive conductive rubber member. However, since the pressure-sensitive conductive rubber member has appropriate flexibility, the load-unloading test is repeated. Even in such a case, it is excellent in output reproducibility and can be applied as a pressure-sensitive sensor.

  In Example 9, due to the large elastic modulus ratio E2 / E1, the rubber elasticity is inferior, the uniformity of the contact state with the electrode is slightly inferior, and the reproducibility when the load-unloading test is repeatedly performed. Tend to be inferior. In addition, when a certain force is applied to the sensor, it is difficult to maintain a uniform contact state, and the output tends to change with time, but as a pressure-sensitive conductive rubber member, it has moderate flexibility, Hysteresis loss is excellent, and it can be applied as a pressure-sensitive sensor.

  In Comparative Example 1, due to the large elastic modulus ratio E2 / E1, the rubber elasticity is inferior, the contact state with the electrode is inferior in uniformity, and the reproducibility when the load-unloading test is repeatedly performed. It is inferior. In addition, it is difficult to maintain a uniform contact state when a constant force is applied to the sensor, and the output changes greatly with time, indicating that it is not suitable as a pressure-sensitive sensor.

  In Comparative Example 2, since a resin with low flexibility is used as the base material of the resin coating film, the uniformity of the contact state with the electrode is inferior, and the reproducibility when the load-unloading test is repeatedly performed. It is inferior. In addition, it is difficult to maintain a uniform contact state when a constant force is applied to the sensor, and the output changes greatly with time, indicating that it is not suitable as a pressure-sensitive sensor.

  In Comparative Example 3, the pressure-sensitive conductive rubber member has a low elastic modulus. When a constant force is applied to the sensor, the amount of deformation gradually increases, and the output changes greatly with time. It can also be seen that a strong hysteresis loss occurs due to the adhesiveness of the pressure-sensitive conductive rubber member, which is not suitable as a pressure-sensitive sensor.

  The pressure-sensitive conductive rubber member of the present invention can be suitably used as a sensor for measuring the magnitude and distribution state of the applied pressure acting on the member by forming the pressure-sensitive conductive rubber member of the present invention into a desired shape and bringing it into contact with a comb-shaped electrode, for example.

1a Pressure-sensitive conductive rubber member 1a-1 Rubber substrate 1a-2 Resin coating 1b Pressure-sensitive conductive rubber member 1b-1 Rubber substrate 1b-2 Resin coating 1c Pressure-sensitive conductive rubber member 1c-1 Rubber substrate 1c- 2 Resin coating 2a Comb electrode 2a-1 Wiring 2a-2 Substrate 2b Square plate electrode 2b-1 Wiring 2b-2 Substrate 3a Pressure sensor 3b Pressure sensor 4-1 Comb electrode 4-2 Pressure sensitive conductive rubber Member 4-3 Insulating sheet 4-4 Voltage measuring instrument 4-5 1 kΩ resistor 4-6 DC voltage generator 5V
4-7 Load measuring instrument

Claims (4)

By detecting the change in the conduction resistance of the pressure sensitive conductive rubber member and the electrode in response to changes in load, Oite pressure-sensitive sensor that senses a load, sensitive pressure sensors, flat rubber substrate a and the pressure sensitive conductive rubber members that will be formed by at least two layers comprising a resin coating containing a conductive agent, an electrode facing contact with the resin coated surface of the photosensitive-pressure conductive rubber member, a dynamic ultra-micro Of the elastic modulus measured by a hardness meter, when the elastic modulus of the rubber substrate is E1, and the elastic modulus of the pressure-sensitive conductive rubber member on the surface on which the resin coating film is formed is E2, E1 is 0.00. A pressure-sensitive sensor , wherein 5 MPa or more and 30 MPa or less , E2 is 10 MPa or more and 700 MPa or less, and a ratio of elastic modulus E1 and elastic modulus E2 is 1 <E2 / E1 <1,000 . The pressure-sensitive sensor according to claim 1, wherein the elastic modulus E2 is 50 MPa or more and 600 MPa or less . The pressure-sensitive sensor according to claim 1 or 2, wherein the elastic modulus E1 is 1.0 MPa or more and 20 MPa or less . A pressure sensor according to one of either 請 Motomeko 1-3, the pressure-sensitive sensor, wherein the electrode is a flexible printed circuit board.